Embodiments of the present invention generally relate to “keyboard percussion instruments”, such as marimbas, vibraphones and xylophones, which have resonators in proximity to tone bars. Specific embodiments pertain to improved resonators and instruments incorporating improved resonators.
The genre of keyboard percussion instruments is also known as “bar percussion instruments” or “tuned mallet instruments”. With the exception of the glockenspiel (“orchestra bells”), which traditionally have their bars made of steel, the tone bars of the keyboard percussion instrument family generally do not produce sufficient volume for musical performance, without amplifying the acoustic output of the tone bar with a similarly tuned resonator in proximity to the tone bar.
In the field of keyboard percussion instruments such as marimbas, vibraphones, xylophones and glockenspiels, many different sizes, shapes and methods of amplifying the tone bars have been developed. Going back into the early part of the last century, Deagan, and Liebich experimented with resonator designs. These inventions mainly concern small high-pitched instruments where the resonator needed to fit directly under the tone bar and in the same parallel plane. U.S. Pat. No. 3,858,477 issued to Kawakami discusses two-part rectangular boxes extending beneath the tone bars and then turning at right angles. The purpose of such an arrangement is said to save space and allow an instrument to be of “small height”.
U.S. Pat. Nos. 4,570,525; 4,941,386 and 5,189,236 pertain to the fine tuning adjustment of the fundamental pitch of tubular resonators. While all three methods have been used successfully in the real world to adjust for temperature and humidity conditions (which change the frequency of both the bars and tubes, but in opposite directions), they do not address the more basic shortcomings of the shape and construction of the resonator itself. U.S. Pat. No. 3,649,737 issued to Jespersen dispenses with the resonators entirely, preferring a pickup coil, amplifier and speaker arrangement. While this might be a viable solution for amplified music styles such as jazz and popular music, players of keyboard percussion instruments more often play music of a type where it is inappropriate to amplify the sound.
It should be noted that all musical instrument manufacturers of keyboard percussion instruments currently use tubes that are stopped at one end—which already shortens the required length of the resonator by half—so no further reductions in length are obtainable. The only other methods are to be found by increasing the volume in other dimensions or by curving the tubes back up before they reach the floor. It is well known that it is more difficult to produce good musical results from the low notes than from the mid and high ranges. While the mid and high ranges of keyboard percussion instruments have traditionally been provided with straight tubular resonators, as the range expanded into lower notes, there is not sufficient room between the tone bar and floor to fit the required straight length of tubing. For instance, the lowest resonator on a 5-octave marimba that can be fit under a standard height keyboard is the “A” below middle “C” which is approximately 31 inches in length. Below this musical range, the designer must find another way to acoustically resonate the tone bar in the space available.
Another factor limiting the possible solutions is the size and spacing of the tone bars. Bass register tone bars must be of sufficient width to produce enough power to couple properly with the associated resonator. Generally speaking, a wider tone bar “moves more air”. All other things being equal, a wider tone bar design will produce more usable volume out of the resonator. However, the associated resonator beneath the bar cannot be too large in diameter or width (depending on whether the resonator is round, square or rectangular at the opening beneath the bar—all of which are currently used by today's musical instrument manufacturers), or the bar will not be able to set the volume of air into vibration except by a very heavy stroke of the mallet. On the other hand, if the resonator is too narrow in diameter or width, the resonator will be set into sympathetic vibration more easily, but the resulting tone will be of weak volume and unsatisfactory in a concert hall.
Yet another factor is the intervallic reach of the player's mallets. For many years, keyboard percussion instruments have been played by musicians holding four mallets—two in each hand (two and six mallet repertoire being less common and therefore not as relevant to design considerations). The larger the width of the bar and resonator combination, the “bigger” the sound, but the more difficult it is for the player to span the distance between two notes played in one hand. It is generally accepted by those skilled in the art of designing keyboard percussion instruments that the size of the lowest octave must be of a distance that can be spanned by the two mallets in the player's left hand.
Two of the biggest percussion instrument companies in the field (Yamaha Corporation and the European company Adams), as well as some smaller firms, use a resonator shape that they refer to as a “Helmholtz Resonator” (after Herman L. F. von Helmholtz, 1821-1894 who first described a similar type of resonator and was the author of On the Sensations of Tone, published in 1862). This shape was originally introduced by a small Japanese company named Korogi in the 1980's. These resonators are generally made of sheet metal rather than round tubing and are rectangular at the opening near the tone bar, flat-sided, and sometimes even flaring into a three-dimensional trapezoidal shape at the closed bottom. FIG. 1 shows an example of this type of resonator.
The original Helmholz resonator was a sphere with a hole or neck and was intended to pick out and resonate a single frequency from a more complex sound. Such a design would be unsatisfactory for amplifying tone bars of keyboard percussion instruments because of the limited volume potential. Instead of selecting a single frequency like the original Helmholtz resonator, instrument designers have adopted the idea to keyboard percussion by using rectangular tubing connecting to sloping sides, continuing to refer to these new and varied shapes as “Helmholtz Resonators”, as shown in FIG. 1. These irregular shapes dramatically increase the complexity of the harmonic content of the resonator from one frequency to almost infinite harmonics. Unlike the original sphere with a hole in it, these irregular shapes “reduce the selectivity” of the frequencies they resonate and somewhat widen the range of the fundamental pitches that can be obtained. When an air stream is forced across the open face a huge array of harmonics is heard—something more like a noise than a musical tone. However, when a tone bar is set in motion with a mallet above, the fundamental frequency of the bar does find a mode to vibrate, along with many other frequencies contained in the tone bar.
Another design rich in harmonics is offered by the American manufacturer “Marimba One”. In this design, a teardrop/elliptical shape is chosen instead of a more harmonically neutral round tube. Because of the lack of a focused fundamental frequency in such a shape, the manufacturer adds something like an organ builder's “Haskill” pipe inside the teardrop shape. This pipe within a pipe helps to clarify the vast array of harmonics into a more responsive order and adds to the effective length of the tube. FIG. 2 shows such a design.
Like in the “Helmholtz” resonators above, when an air stream is forced across the open face a huge array of harmonics is heard—again, something more like a noise than a musical tone. However, when a tone bar is set in motion with a mallet above, the fundamental frequency does find a mode to vibrate, along with many other frequencies contained in the tone bar.
There are also round tubular solutions available from Steinway's Musser Marimba division, Yamaha and Malletech, for example. In each of these solutions, 22.5° angled sections of round tubing are welded, brazed or soldered together. These designs have 4 welded joints connecting the 5 sections of tubing. FIGS. 3A-3C show examples of such configurations. FIG. 3A shows a substantially J-shaped first octave C resonator 10 for a keyboard percussion instrument. FIG. 3B shows a substantially U-shaped first octave C sharp resonator 20 for a keyboard percussion instrument. FIG. 3C shows a substantially L-shaped first octave F-sharp resonator 30 for a keyboard percussion instrument. As will be seen from a review of FIGS. 3A-3C, each of these resonators includes a number of joined sections. The L-shaped resonator 30 shown in FIG. 3C comprises three sections 32, 34, and 36 joined together and has two joints 33 and 35, whereas, the U-shaped resonator 20 in FIG. 3B comprises five sections 22, 24, 26, 28, and 39 and four joints 21, 23, 25 and 27. In FIG. 3A, the J-shaped resonator also comprises five sections 12, 14, 16, 18, 19 and four joints 11, 13, 15 and 17. As noted above, each of the sections are joined at 22.5° angles with respect to each other.
Established thinking in the field assumes that a 5-section design offers the best of 2 worlds: it adheres to the basics tenets of fluid dynamics that promise easier flow through a gentle bend, while offering many internal facets at the joints that can reinforce the resonance and enrich the harmonic content of the resultant tone. When a stream of air is blown across the open face of this type of resonator, a clear fundamental pitch is heard, along with both harmonic and non-harmonic components.
While these various resonator designs have provided acceptable sound, as will be appreciated upon further reading of the details of the present invention, it would be desirable to provide a resonator that reduces or eliminates non-harmonic components. It would be desirable to provide improved resonators for keyboard percussion instruments that do not suffer from one or more of these disadvantages.